Description
Meesmann corneal dystrophy is an eye disease that affects the cornea, which is the clear front covering of the eye. This condition is characterized by the formation of tiny round cysts in the outermost layer of the cornea, called the corneal epithelium. This part of the cornea acts as a barrier to help prevent foreign materials, such as dust and bacteria, from entering the eye.
In people with Meesmann corneal dystrophy, cysts can appear as early as the first year of life. They usually affect both eyes and increase in number over time. The cysts usually do not cause any symptoms until late adolescence or adulthood, when they start to break open (rupture) on the surface of the cornea and cause irritation. The resulting symptoms typically include increased sensitivity to light (photophobia), twitching of the eyelids (blepharospasm), increased tear production, the sensation of having a foreign object in the eye, and an inability to tolerate wearing contact lenses. Some affected individuals also have temporary episodes of blurred vision.
Frequency
Meesmann corneal dystrophy is a rare disorder whose prevalence is unknown. It was first described in a large, multi-generational German family with more than 100 affected members. Since then, the condition has been reported in individuals and families worldwide.
Causes
Meesmann corneal dystrophy can result from mutations in either the KRT12 gene or the KRT3 gene. These genes provide instructions for making proteins called keratin 12 and keratin 3, which are found in the corneal epithelium. The two proteins interact to form the structural framework of this layer of the cornea. Mutations in either the KRT12 or KRT3 gene weaken this framework, causing the corneal epithelium to become fragile and to develop the cysts that characterize the disorder. The cysts likely contain clumps of abnormal keratin proteins and other cellular debris. When the cysts rupture, they cause eye irritation and the other symptoms of Meesmann corneal dystrophy.
Inheritance
This condition is inherited in an autosomal dominant pattern, which means one copy of an altered KRT12 or KRT3 gene in each cell is sufficient to cause the disorder. In most cases, an affected person inherits the condition from an affected parent.
Other Names for This Condition
- Corneal dystrophy, juvenile epithelial of Meesmann
- Corneal dystrophy, Meesmann epithelial
- Juvenile hereditary epithelial dystrophy
- MECD
- Meesman's corneal dystrophy
- Meesmann corneal epithelial dystrophy
- Meesmann epithelial corneal dystrophy
Additional Information & Resources
Genetic Testing Information
Genetic and Rare Diseases Information Center
Patient Support and Advocacy Resources
Catalog of Genes and Diseases from OMIM
Scientific Articles on PubMed
References
- Corden LD, Swensson O, Swensson B, Smith FJ, Rochels R, Uitto J, McLEAN WH. Molecular genetics of Meesmann's corneal dystrophy: ancestral and novel mutations in keratin 12 (K12) and complete sequence of the human KRT12 gene. Exp Eye Res. 2000 Jan;70(1):41-9. doi: 10.1006/exer.1999.0769. Citation on PubMed
- Ehlers N, Hjortdal J, Nielsen K, Thiel HJ, Orntoft T. Phenotypic variability in Meesmann's dystrophy: clinical review of the literature and presentation of a family genetically identical to the original family. Acta Ophthalmol. 2008 Feb;86(1):40-4. doi: 10.1111/j.1600-0420.2007.00931.x. Epub 2007 Nov 6. Citation on PubMed
- Irvine AD, Corden LD, Swensson O, Swensson B, Moore JE, Frazer DG, Smith FJ, Knowlton RG, Christophers E, Rochels R, Uitto J, McLean WH. Mutations in cornea-specific keratin K3 or K12 genes cause Meesmann's corneal dystrophy. Nat Genet. 1997 Jun;16(2):184-7. doi: 10.1038/ng0697-184. Citation on PubMed
- Klintworth GK. Corneal dystrophies. Orphanet J Rare Dis. 2009 Feb 23;4:7. doi: 10.1186/1750-1172-4-7. Citation on PubMed or Free article on PubMed Central
- Nishida K, Honma Y, Dota A, Kawasaki S, Adachi W, Nakamura T, Quantock AJ, Hosotani H, Yamamoto S, Okada M, Shimomura Y, Kinoshita S. Isolation and chromosomal localization of a cornea-specific human keratin 12 gene and detection of four mutations in Meesmann corneal epithelial dystrophy. Am J Hum Genet. 1997 Dec;61(6):1268-75. doi: 10.1086/301650. Citation on PubMed or Free article on PubMed Central
- Smith F. The molecular genetics of keratin disorders. Am J Clin Dermatol. 2003;4(5):347-64. doi: 10.2165/00128071-200304050-00005. Citation on PubMed
- Szaflik JP, Oldak M, Maksym RB, Kaminska A, Pollak A, Udziela M, Ploski R, Szaflik J. Genetics of Meesmann corneal dystrophy: a novel mutation in the keratin 3 gene in an asymptomatic family suggests genotype-phenotype correlation. Mol Vis. 2008 Sep 15;14:1713-8. Citation on PubMed or Free article on PubMed Central
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